The invention relates to stair or ladder steps of the plate-shaped step type, where plate members bent downwards are provided at all four rims of the stepping surface, i.e., at the front rim, the rear rim, and the two side rims. The downwardly bent rims are welded together at the corners where said plate members abut one another due to the bending.
Stair or ladder steps of the above shape are known, for instance from the products previously sold by the Applicant, as illustrated in sales brochures.
Such stair or ladder steps are usually secured between the stringers by bolts extending through openings in each of the two plate members bent downwards at the side rims, and then further extending through openings in the respective adjacent stringers. Obviously, the ladder steps can, also be secured to the stringers in other ways, such as by welding.
Such a stair necessitates a predetermined height of the individual steps, this height corresponding to the width of the plate members bent downwards, in order to ensure that the steps can stand the required loads. Thus an opening is provided between the stepping surface of a step and the lower rim of the front rim bent downwards of the step just thereabove. This opening presents an undesired xe2x80x9cfoot trapxe2x80x9d because a foot can get jammed in this opening or be injured by the rather sharp plate rim.
When the width of the front rim is low in such a manner that the step is of a low height and the above opening is therefore sufficiently large for avoiding the foot trap, the resulting step does not have a sufficient strength. On the other hand, when the front rim extends to the stepping surface of the step therebelow, the consumption of material is relatively extensive and the stepping surface is not particularly wide, although the foot trap has indeed thereby been avoided.
The object of the invention is to provide stair or ladder steps of the above type, with improved utilization of the materials compared to previously known steps of the plate-shaped step type, this utilization of the materials being expressed by the relationship of the strength and weight of a step, and in which the xe2x80x9cfoot trapxe2x80x9d involved when the step forms part of a stair structure is avoided.
In stair or ladder step according to the invention, the plate member bent downwards at the front rim is rolled over to form a cylindrical pipe.
In this manner, the sharp plate rim is avoided at the front rim bent downwards, and furthermore the foot trap is avoided because plenty of room is provided for a foot. In addition, the step is provided with a rather high strength.
The plate member bent downwards at the rear rim is also rolled over to form a cylindrical pipe, thereby providing further reinforcement of the step. In addition, the front rim and the rear rim can be identical, with the result that the stair or ladder step can be turned 180xc2x0 about a vertical axis of symmetry in connection with the mounting procedure.
Further reinforcement of the step may be obtained by also welding the locations where the ends of the cylindrical pipes abut the plate members bent downwards at the side rims.
It is, of course, possible to use several types of soundproofing materials, but polyurethane foam turned out to be extremely advantageous for the purpose.